Crack monitoring of pavements is an ever-evolving technology with new crack identification technologies being introduced frequently. Although older technologies consisted of physical removing the pavement section using coring, however new methods are available that are non-destructive and yield a higher performance than conventional technologies. This paper compiles various crack monitoring technologies such as wireless sensor networks, photo imaging, laser imaging, 3D road surface profile scans, acoustics wave propagation technology, embedded strain sensors and onboard vehicle sensors that majorly use an artificial intelligence algorithm to identify and categorize the cracks. The research also includes the use of convolutional neural network that can be used to analyze pavement images and such neural network can localize and classify the cracks for crack initiation and propagation stage. The research concludes with the favor of using the optical imaging technology called Syncrack which serves better performance in terms of time of prediction by 25% and accuracy by 30% when compared to other sensing technologies.
This research investigates the efficiency of Ultrasonic Pulse Velocity (UPV) method in detecting voids and depth of cracks in concrete. Tests were performed to compare the accuracy between the direct and indirect method of Ultrasonic Pulse Velocity method (UPV) in detecting the location of defects. Three concrete prisms with fabricated void at a known location were used and tested at 28 day. Two other prisms were casted and tested to detect of crack depth in concrete, cracks at depth of 5 and 10 cm perpendicular to axis of beam were induced without actually breaking the beam. Test results indicate that direct and indirect methods can be used to assess the in-situ properties of concrete or for quality control on site, and the first and second method of determining the crack depth gave results with high accuracy while the results of third method were lower than the actual crack depth and for the forth method were higher than it. Therefor, we can use the average of the third and forth results to obtain the crack depth with good accuracy.
The principal objective of this paper is to investigation the experimental of the flexural behavior of strengthened and repaired reinforced concrete slabs with ferrocement tension zone. The result of tests on 10 simply supported one way slabs were presented, at which include 1control slab, 5strengthened slabs and 4repaired one way slabs. In the strengthened slabs, the cover of the control slab replacing with ferrocement cover, cold joint between ferrocement layer and the slab, connection type between the ferrocement layer and the slab, on the ultimate load, first crack load, the mid span-deflection, crack width and spacing were examined. In the repaired part the slabs were loaded to (55 %) of measured ultimate load of control slab, the effect of the thickness and number of wire mesh layers on crack pattern, mid span deflection and ultimate load was examined. In the repaired part the slabs were loaded to (55 %) of measured ultimate load of control slab, effect of the number of wire mesh layers of ferrocement on the mid span deflection, ultimate load and crack pattern was examined. The experimental results of strengthened and repaired slabs indicate that; the ultimate loads and mid span deflection were more effected by using ferrocement mortar at tension zone. The increase in ultimate load (8.2-18%) for strengthen slab and (9.1-17.3%) for repaired slab respect to the control slab.
In the civil engineering, the prediction of cracks for tunnel lining is too hard because it depends by different factors for example concrete strength, tunnel operation conditions, stress and geological surroundings. The aim of this study is to design a Fuzzy inspect System (FIS) for evaluating the concrete cracks of tunnel lining. Fuzzy logic is a method to signify a type of uncertainty which is understandable for user. The system has been designed to meet permit crack formula that issued in “Highway Tunnel Design Specifications”. When the maximal permit crack width as example is chosen as 0.7mm, 1.2mm and 3.3mm separately the fuzziness set accordingly is Minor , moderate and severe. The average error for the predicted crack (element sample) in FIS is 8.34%. The fuzzy evaluation model is based on the information of a real in-service PESHRAW highway tunnel, which reflects field status. Therefore, this evaluation is comfortable.
This paper presents the experimental results of eight slabs made of Ferrocement. All specimens were )700mm (long, )300mm (wide and )50mm (thick. These specimens were divided into two groups (The first group has four specimens coursed of normal sand gradient and in the other four specimens, the sand that passing from sieve No. 8 was neglected), to investigate behavior of slabs under bending effect and studying the cracks that generated after bending then, comparing the results between these two groups. A thin square welded wire mesh was used as reinforcement. The number of wire mesh layers was varied between 0 to 3 layers. Ultrasonic Pulse Velocity (UPV) Test was used to detect the cracks. The results showed that there was a slight rise in bending for first group slabs compared with second group slabs. Maximum bending strength was achieved for both slab groups with 3 layers of wire mesh. it was shown that there was a significant convergence in the load values required to cause appearing of the first crack and final failure for the two groups. The percentage of ultimate load between slab reinforced with 3 layers and without reinforcement was (25.27%) for the first group, while the increase in ultimate load for a specimen that reinforced with 3 layers was (24.16%) compared to specimen without reinforcement for the same group. On the other hand, the results showed an improvement in the performance of the second group slabs due to its resistance to appearing of cracks resulted from bending. The percentage of increasing cracks after bending for the unreinforced specimen in group 1 was (9%) compared with the unreinforced slab in group 2. Whereas the numbers of cracks number in slab reinforced with 1 and 2 layers in the second group were less than slabs with 1 and 2 layers in the first group about (8.86 %) and (7.77%), respectively. While this percentage for a specimen with 3 layers in group 2 was about (8.62%) less compared to the specimen with 3 layers in group 1..
AbstractDeflection of partially prestressed concrete beams is investigated using the finite element method taking in to account the plasticity of steel, nonlinearity of concrete in compression and tension softening of concrete. Embedded bar approach is used to represent the steel reinforcement and prestressing tendon in concrete layer. Elastic perfectly-plastic approach has been employed to model the compressive behaviour of the concrete.The yield condition is formulated in terms of the first two-stress invariants. The movement of the subsequent loading surfaces is controlled by the hardening rule, which is extrapolated from the uniaxial stress-strain relationship defined by a parabolic function. Concrete crushing is a strain controlled phenomenon, and can be monitored by a fracture surface similar to the yield surface. A smeared fixed crack approach is used to model the behaviour of the cracked concrete, with a tensile strength criterion to predict crack initiation. The steel is considered as an elastic perfectly plastic material with linear strain hardening, steel reinforcement is assumed to have similar tensile and compressive stress-strain relationship. The calculated and the observed effects have shown a satisfactory agreement compared with experimental results.
Composite beams, made up of a concrete slab and steel in the IPE steel section, are commonly used in bridges and buildings. Their main function is to enhance structural efficiency by merging the compressive strength of concrete with the tensile resistance of steel, thereby improving overall stiffness, ductility, and load-bearing capacity. This study offers an extensive review of the flexural behavior of steel-concrete composite beams, focusing on the interplay of concrete strength, shear connector types, and interaction levels in determining structural performance. It integrates experimental and numerical research to analyze critical parameters, including load-deflection behavior, shear transfer efficiency, and crack propagation at the steel-concrete interface. The study emphasizes the effect of concrete compressive strength, particularly in ultra-high-performance concrete (UHPC) and lightweight concrete, on stiffness, ductility, and load-bearing capacity while reducing self-weight and enhancing sustainability. The study revealed that fully bonded shear connectors, using CFRP sheets and welded plates, enhance flexural capacity and stiffness. In contrast, partial bonding or pre-debonding reduces performance due to crack propagation. Indented and hot-rolled U-section connectors enhance interaction and minimize slip, while uniform distribution of shear connectors optimizes load capacity and stiffness. Lightweight concrete decreases slab weight without compromising performance, and high-performance materials such as ECC, SFRC, and UHPFRC improve strength and ductility. Numerical modeling, particularly finite element methods, and higher-order beam theories validate experimental results, providing accurate tools for predicting structural behavior under various loading and environmental conditions.
AbstractA full three dimensional finite element computational model is constructed for nonlinear analysis of reinforced concrete curved beams. This model was presented utilizing computer program ANSYS (Version 11), which is capable of an efficient analysis of the response at different load levels including ultimate loads.This work deals with the structural analysis of concrete curved beams behaviour subjected to two concentrated loads. Concrete curved beams are widely used in building and bridge constructions. Some of the available experimental tests on reinforced concrete curved beams are theoretically analyzed. This covers load-deflection relationships, crack pattern and propagation of crack at different stages of load and ultimate load capacity. The reliability of the model is demonstrated by comparison with available experimental results and alternative numerical analyses which shows 4 – 8 % difference.
This research investigates the impact resistance of concrete slabs with different volume perecentage replacement ratios of waste plastic fibers (originaly made from soft drink bottles) as follows : 0.5%, 1% and 1.5%. Reference mix produced in order to compare the result. For the selected mixes, cubes with (100×100×100mm) were made to test compressive strength at age of (90) days. Flexural strength (Modulus of Rupture) test was also conducted using prisms sample of (500*100*100 mm) dimensions. The low-velocity impact test was conducted by the method of repeated falling mass where 1400gm steel ball was used. The ball falling freely from height of 2400mm on concrete panels of (500×500×50 mm) having a mesh of waste plastic fiber.The number of blows that caused first crack and final crack (failure) were determined, according to the former obtained results , the total energy was calculated. Results showed an improvement in mechanical properties for mixes containing plastic fibers compared with reference mix. For compressive strength the maximum increase in compressive strength was equal to (3.2%) at age of (90) days. Flexural strengths for mixes containing plastic fiber at ages 28, and 90 days are higher than that of these of reference mix. The maximum value of increaseing was (18%) for 28 days age of test and it was equal to (26%) for 90 days age of test for the mixture with plastic fiber content by volume equal to (1%) . Results showed a significant improvement in low-velocity impact resistance of all mixes contining waste plastic fibers when comparing with reference mix. Results illustrated that mix with (1.5%) waste plastic fibers by volume give the higher impact resistance at failure than the others. The magnitude of an increase over reference mix was equal to (340%).
This study presents an experimental investigation performed to investigate the using of steel fiber reinforced concrete (SFRC) as an alternative to negative reinforcement in continuous RC thin slab panels. More rational way has been used by replacing negative reinforcement near interior supports by steel fiber reinforced concrete (SFRC). Tests were carried out on four slab panels, simply supported under single point loading. One of which were made fully with NSC, and the others were made partially with SFRC in negative moment zone. Experimental results show that the ultimate load capacity are increased (23% -58%) and the cracking loads are increased (25% -62.5%) for tested specimens strengthened with SFRC, in comparison with the reference specimens. Crack arrest mechanism of steel fibers limits crack propagation, improves the ultimate and tensile strength. So, more practical technique can be concluded from this study and employed in manufacturing of thin slabs.
This paper investigates the results of finite element analysis for three proposed full-scale two-way slabs. The aim of this study is to use finite element method (FEM) by using ANSYS-v15 program to analyze the proposed slabs and study the flexural behavior , especially load-deflection relationship and ultimate strength. Some parametric studies on these works are also done to cover the effect of some important parameters on the ultimate load capacity and deflection. Proposed slabs are divided into three groups with different dimensions to study the effect of using continuous large spans on the structural behavior of two-way ribbed (waffle) slabs as compared to solid slabs. In all three groups, each slab consists of three by three panels supported by concrete columns at corners. For the first group, when the void ratio (the ratio of volume of voids between ribs to total volume of ribbed slab) increases, the stiffness of waffle slab also increases. Increasing stiffness for waffle slab is continued up to some limit, and then will decrease with increasing void ratio. The best case in this example occurs when the void ratio equal to (0.667) which gives increase in stiffness of (0.347) as compared to solid slab with the same thickness. The results of ANSYS analysis shows that the best percentage of increase in deflection is (51%) with decreasing in concrete volume of (59%) for long to short span ratio of (1.5) and (300)mm thickness. For the third group of proposed models, the stiffness of two-way ribbed (waffle) slab is higher than the solid slab which has the same volume of concrete. The displacement of two-way ribbed (waffle) slab in the elastic range (at first crack ) is lower than the solid slab. In this manner, it will give the maximum reduction in concrete weight with higher thickness.
An experimental investigation was conducted to study the strength, behaviour and deflection characteristics of two way slabs made with both self-consolidating concrete (SCC) and conventional concrete (CC). Six concrete slabs were tested to failure under simply supported uniform by distributed loading conditions. The variables were concrete type and macro synthetic fibres ratio (0%, 0.07% and 0.14%). The performance was evaluated based on crack pattern, ultimate load, load-deflection response and failure mode. The results showed that the ultimate strength of SCC slabs was larger than that of their CC counterparts. The results also showed an improvement of the behaviour and strength of slabs by adding the synthetic fibres.
Adding fibers to the shotcrete concrete mixes is very important to increase the load carrying capacity, toughness, and reducing crack propagations by bridging the cracks. On the other hand, this fiber has an effect on the fresh and hardened properties of shotcrete. In this study, fresh properties evaluated by using slump flow, , and segregation resistance tests. Hardened properties included testing of air voids, dry density, water absorption, ultrasonic pulse velocity (UPV), compressive strength, and flexural strength. This works including two types of fibers in three forms (waste plastic (PET)fibers only, polypropylene fibers (PP) only, and hybrid fiber (PET and PP)), each form added by three percentages (0.35%, 0.7%, and 1%) by volume.The results showed that the addition of 1% of all types of fiber has a negative impact on fresh properties. Especially in shotcrete containing waste plastic fiber. Also, all specimens containing fibers showed a decrease in the ultrasonic pulse velocity (UPV) and an increase in air voids and water absorption compared to the reference specimens. Also, the results clarify that the addition of waste plastic fiber to shotcrete led to a slight decrease in dry density. The highest increasing in compressive strength of shotcrete recorded by about 8.2% with using 0.35% PP fiber and highest decreasing was 20.9% with using 1% waste plastic fiber. the highest increasing in flexural strength was 62 with using 1% PP fibers.
This paper deals with the nonlinear finite element analysis of two shear-critical concrete dapped-end beams. Reinforced concrete dapped-end beams having nominal shear span to depth ratio values of 0.56 and 0.59, concrete strength 32MPa and 34MPa, and reinforcement ratio via yield strength 2.83MPa and 7.39MPa, that failed in shear have been analyzed using the ‘ANSYS’ program. The ‘ANSYS’ model accounts for the nonlinearity, such as, post cracking tensile stiffness of the concrete, stress transfer across the cracked blocks of concrete. The concrete is modeled using ‘SOLID65’- eight-node brick element, which is capable of simulating the cracking and crushing behavior of brittle materials. The internal reinforcements have been modeled discretely using ‘LINK8’ – 3D spar element. A parametric study is also made to explain the effects of variation of some main parameters such as shear span to depth ratio, concrete compressive strength, and the parameter of main dapped-end reinforcement on the behavior of the beams. From the present modality the capability of the model to capture the critical crack regions, loads and deflections for various types of shear failures in reinforced concrete dapped-end beams have been illustrated. The parametric study shows that the beams shear strength is affected by the shear span to depth ratio, concrete compressive strength and the amount of main reinforcement.